• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.91-100
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• 2018

Recently, the traditional call center, which has an important role as the customer's primary contact point, has been transformed into the omni-channel contact center which supports an additional variety of access channels in addition to phone calls in order to improve customer accessibility and convenience. The omni-channel contact center has agents on each channel which are vital in determining the response rate and waiting time for the customer. In traditional call centers, agents can be assigned to a call based on the characteristics of the call, however in omni-channel contact centers, the characteristics of issues vary and come in through multiple channels, each with their own characteristics, making it difficult to assign the appropriate agent for the issue. Customers must also be processed at the same time, adding an additional layer of complexity to the issue. This paper analyzes and simulates an omni-channel contact center that accommodates email, chat, voice calls and video consultation, and investigates how to optimize the allocation of agents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.9
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• pp.819-827
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• 1991

In this study, the efficiency of spectrum utilization has compared in case of channel spacking 100 KHz and 200 KHz by application of technical specifications of domestic FM broadcasting varing with effective radiated power, terrain irregularity factor and effective height of thrnsmit antenna. The results show that if arranging by 100 KHz channel total number of available channel will increase twice and the efficiency of spectrum unilization will be better 1.36 to 2.0 times than that of 200 KHz channel spacing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2805-2812
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• 2015

For the purpose of estimation of time variant frequency selective transmission channels, reference symbols are usually employed. The bit error performance of LTE OFDM systems is analyzed in the case of LTE standard reference symbol arrangement. Results show that LTE OFDM system with this LTE reference symbol arrangement is robust against Doppler time variant fading. However, the performance of that system is degraded due to channel estimation error in frequency domain. An equidistant arrangement with a diamond shape structure of reference symbols, however having 4 subcarriers distance in frequency domain, is suggested for the optimal channel estimation.

• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.357-367
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• 2004

In VOD systems the number of channels available to a video server is limited since the number of channels, the video server can support, is determined by the communication bandwidth of the video server. Multicast techniques such as batching, patching and batch-patching have been proposed to reduce I/O demand on the video server by sharing multicast data. In this paper, we propose a channel reservation batch-patching technique that first applies the batching technique to hot video requests and then applies the patching technique to the batches of the hot video requests. And the proposed technique reserves a part of the channel capacity of the video server for many hot video requests, so that the hot video requests can be served without defection. The performance of the proposed technique is compared with those of Patching and Batch-Patching techniques in terms of average service latency, defection rate, fairness and frame reduction rate by simulations.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.1
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• pp.1-4
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• 2015

This paper presents an algorithm for finding valid side chain conformations of amino acids, when given channel is transformed. The suggested algorithm implements a protein molecule with flexible side chains based on the flexibility of amino acids, and extracts adjacent amino acids that affect the formation of the channel. We detect the collision between adjacent amino acids and neighbors, in order to exclude invalid side chain conformations. Then, we construct the rotation angle combination tree to choose valid side chain conformations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.135-141
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• 2011

Analog medias are converting to digital with the development of the digital communications. The Korean radio broadcasting services yet on analog and the research for the digital radio is progressing. The digital conversion of radio broadcasting has already progressed in foreign countries because of the technical limitation of analog broadcasting(The radio-frequency efficiency is poor). DAB is one of the digital radio mode, it doesn't use on AM/FM band and uses on T-DMB frequency band. So, it has an advantage of being able to broadcast with the existing radio without interference at once. On the other hand, it has the potential to cause interference to existing T-DMB broadcasting. In this paper, we propose an efficient DAB channel allocation method for digital radio on T-DMB frequency band. This paper allocates the DAB channel without interference to existing T-DMB broadcasting and proves the proposed method through simulations for the interference analysis.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.207-215
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• 2011

Due to the increasing availability and popularity of digital television (DTV), the numbers of TV channels and programs that can be selected by consumers are also increasing rapidly. Therefore, searching for interesting channels and program via remote controls or channel guide maps can be frustrating and slow. In this paper, in order to better satisfy consumers, we propose a dynamic channel surfing scheme that reduces the channel seek distance in DTV. The proposed scheme dynamically rearranges the channel sequences according to the channel currently being watched to reduce the channel seek distance. The results of a simulation experiment demonstrate that the proposed dynamic channel surfing scheme reduces the channel seek distance for DTV channel navigation when up-down channel selection interfaces are used.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10A
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• pp.941-948
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• 2008

In this paper, the effect of unobtainable channel frequency response (CFR) inside virtual subcarreiers on DFT-based channel estimation is derived and introduced numerically because the CFRs cause the leakage to the estimated channel and degrade the estimation performance. In addition, the performance of DFT-based channel estimation is analyzed with respect to the number of virtual subcarriers, pilot spacing and the number of unobtainable CFRs at equi-distance subcarriers inside virtual subcarriers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.210-218
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• 2010

In order to improve the efficiency of frequency bandwidth, various modulation methods such as QAM and PSK have been widely used, and their variation APSK(Amplitude Phase Shift Keying) type modulation methods were proposed and are being used in some satellite communication systems. In this paper, a new constellation method named as $4L^2$-APSK is proposed, which places symbol points circularly as the existing APSK constellations do, but has different number of points and different distance between adjacent points on each layer. An equation for error probability in AWGN channel is also induced for $4L^2$-APSK. In addition, a new Gaussian noise channel is proposed in which noise variances are in the amplitude and in the phase and the two are not equal, and a method of obtaining error probabilities in this channel is also suggested. The equations for error probabilities are verified by computer simulations, and error probabilities of $4L^2$-APSK and QAM are analyzed and compared in the AWGN channel and the proposed noise channel, respectively.

• Information and Communications Magazine
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• v.17 no.6
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• pp.36-45
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• 2000